Resistivities of metals are

Options

A. `10^-8Omegam`
B. `10^-6Omegam`
C. `10^-8Omega` to `10^-6Omegam`
D. `10^8Omega` to `10^-6Omegam`

Answer

To answer the question regarding the resistivities of metals, we will go through the following steps:

### Step 1: Define Resistivity
Resistivity (denoted by the symbol ρ, rho) is a fundamental property of materials that quantifies how strongly they resist the flow of electric current. It is defined as the resistance of a material per unit length and cross-sectional area.

### Step 2: Understand the Formula
The resistance (R) of a wire can be expressed using the formula:
\[ R = \frac{\rho L}{A} \]
Where:
- \( R \) is the resistance,
- \( \rho \) is the resistivity,
- \( L \) is the length of the wire,
- \( A \) is the cross-sectional area of the wire.

### Step 3: Rearranging the Formula
From the formula, we can rearrange it to express resistivity:
\[ \rho = \frac{R \cdot A}{L} \]
This shows that resistivity is directly proportional to resistance and area, and inversely proportional to length.

### Step 4: Units of Resistivity
The unit of resistivity is ohm-meter (Ω·m). This indicates how much resistance is encountered by a unit length of a conductor with a unit cross-sectional area.

### Step 5: Characteristics of Metals
Metals are known to be good conductors of electricity, meaning they allow electric current to flow through them with minimal resistance. Therefore, the resistivity of metals is relatively low compared to insulators.

### Step 6: Range of Resistivity for Metals
The resistivity of metals typically ranges from:
\[ 10^{-8} \, \text{Ω·m} \, \text{to} \, 10^{-6} \, \text{Ω·m} \]
This range indicates that metals have low resistivity, allowing them to conduct electricity efficiently.

### Conclusion
In summary, the resistivity of metals is low, typically ranging from \( 10^{-8} \, \text{Ω·m} \) to \( 10^{-6} \, \text{Ω·m} \).

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